Clinic #32 is one of the 53 investigative centers participating in the National Cooperative Study of drugs in patients with proven coronary heart disease. The purpose of the study is to test the effectiveness of long-term treatment with selected lipid-lowering drugs in reducing mortality and morbidity in patients between the ages of 30 and 64 years who have had a previous documented myocardial infarction. Another major objective of the study is to learn more about the natural history of coronary heart disease from examination of data in the placebo group of patients. Before admission to the study, with the cooperation of personal physicians, and by history as well as by physical examination and laboratory workup, it was ascertained that the volunteers were not on ancillary drug therapy, and that there were no serious incidental diseases which would interfere with at least a five year life expectancy which is the period of the study. The study has been given a two year expansion and the closing date for Coronary Drug Project is January 31, 1975 at present. After patients were proved acceptable they were randomly allocated into a placebo group and to one of five different treatment groups. However, since the onset of the experiment and because of possible deleterious effect, those patients on high dose estrogen have been transferred to a coded placebo. Allocation of patients was determined by the Coordinating Center in Baltimore, Maryland.